Nonlinear probabilistic finite element models of laminated composite shells

A probabilistic finite element analysis procedure for laminated composite shells has been developed. A total Lagrangian finite element formulation, employing a degenerated 3-D laminated composite shell with the full Green-Lagrange strains and first-order shear deformable kinematics, forms the modeling foundation. The first-order second-moment technique for probabilistic finite element analysis of random fields is employed and results are presented in the form of mean and variance of the structural response. The effects of material nonlinearity are included through the use of a rate-independent anisotropic plasticity formulation with the macroscopic point of view. Both ply-level and micromechanics-level random variables can be selected, the latter by means of the Aboudi micromechanics model. A number of sample problems are solved to verify the accuracy of the procedures developed and to quantify the variability of certain material type/structure combinations. Experimental data is compared in many cases, and the Monte Carlo simulation method is used to check the probabilistic results. In general, the procedure is quite effective in modeling the mean and variance response of the linear and nonlinear behavior of laminated composite shells

Interlaminar shear stress effects on the postbuckling response of graphite-epoxy panels

The influence of shear flexibility on overall postbuckling response was assessed, and transverse shear stress distributions in relation to panel failure were examined. Nonlinear postbuckling results are obtained for finite element models based on classical laminated plate theory and first-order shear deformation theory. Good correlation between test and analysis is obtained. The results presented analytically substantiate the experimentally observed failure mode

Bridging the gap by shaking superfluid matter

In cold compact stars, Cooper pairing between fermions in dense matter leads to the formation of a gap in their excitation spectrum and typically exponentially suppresses transport properties. However, we show here that weak Urca reactions become strongly enhanced and approach their ungapped level when the star undergoes density oscillations of sufficiently large amplitude. We study both the neutrino emissivity and the bulk viscosity due to direct Urca processes in hadronic, hyperonic and quark matter and discuss different superfluid and superconducting pairing patterns.Comment: 5 pages, 4 figure

Effect Of Ph On The Physical Properties Of Znin2se4 Thin Films Grown By Chemical Bath Deposition

Recently there has been much interest on the preparation and characterization of ternary semiconducting materials, mainly ZnIn2Se4 (ZIS) due to its potential applications in various fields, particularly as a buffer layer in the fabrication of heterojuction solar cells. In the present work, thin films of ZIS have been synthesized by a simple and economic method, chemical bath deposition at different pH values that vary from 9 to 11. The deposition was carried out for a fixed bath temperature (Tb) of 90 °C and constant reaction time of 60 min. Ammonia and hydrazine hydrate were used as complexing agents. The chemical and physical properties of the deposited ZIS films were analyzed using appropriate techniques. The X-ray diffraction analysis revealed that the deposited films were polycrystalline and showed (112) peak as the preferred orientation. Scanning electron micrographs revealed that the samples had large number of granule like particles in different sizes. The optical transmittance of these samples was found to be > 75 % in the visible region and the evaluated energy band gap varied from 2.15 eV to 2.64 eV with the change of pH value in the range, 9 - 11. The detailed study of these results were presented and discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/939

Noise characteristics of upper surface blown configurations: Analytical Studies

Noise and flow results of upper surface blown configurations were analyzed. The dominant noise source mechanisms were identified from experimental data. From far-field noise data for various geometric and operational parameters, an empirical noise prediction program was developed and evaluated by comparing predicted results with experimental data from other tests. USB aircraft compatibility studies were conducted using the described noise prediction and a cruise performance data base. A final design aircraft was selected and theory was developed for the noise from the trailing edge wake assuming it as a highly sheared layer

Why PPP Modeled Infrastructure Projects Failed:A Critical Review with a Special Focus on Road Sector

Infrastructure is the back bone of economic development of any Nation. Road infrastructure plays key role for trade and commerce, connecting the production and consumption centers. Road and transportation infrastructure construction is highly capital intensive, wherein the government alone cannot meet its ends and initiated Public Private Partnership (PPP) for its execution right from planning and designing to its maintenance through various PPP models. Over the last few years many of the awarded roadprojects through PPP modelare stalled citing various reasons. This technical paper analyses the risk factors associated with PPP –toll operated road projects through case studies and suggested corrective measures like shadow tolling and hybrid models for restoration of PPP

Carrier induced ferromagnetism in concentrated and diluted local-moment systems

For modeling the magnetic properties of concentrated and diluted magnetic semiconductors, we use the Kondo-lattice model. The magnetic phase diagram is derived by inspecting the static susceptibility of itinerant band electrons, which are exchange coupled to localized magnetic moments. It turns out that rather low band occupations favour a ferromagnetic ordering of the local moment systems due to an indirect coupling mediated by a spin polarization of the itinerant charge carriers. The disorder in diluted systems is treated by adding a CPA-type concept to the theory. For almost all moment concentrations x, ferromagnetism is possible, however, only for carrier concentrations n distinctly smaller than x. The charge carrier compensation in real magnetic semiconductors (in Ga_{1-x}Mn_{x}As by e.g. antisites) seems to be a necessary condition for getting carrier induced ferromagnetism.Comment: 9 pages (REVTeX), 6 figures, to be published in Phys. Rev.